The electric utility industry employs socket-type watt-hour meters to measure electric power consumption, commonly mounted on a wall of residential, commercial and industrial buildings. These type of watt-hour meters contain terminals which are connected to the electric line or to electric load conductors. The terminals are also connected to internal conductors within the socket, which extend to jaw contacts positioned to receive the blade terminals of a plug-on watt-hour meter to complete an electric circuit through the watt-hour meter between the line and load terminals and the conductors.
The socket-type watt-hour meter has a ring-type cover, which includes some annular mounting flanges projecting outwardly from an opening through which the blade terminals of the watt-hour meter extend. Both mounting flanges are maintained together by means of the meter ring and the base housing. Once assembled they are encircled by the security sealing ring, thereby sealing the single-phase or polyphase watt-hour meter to the base.
A common type of belt seal for socket-type watthour meter usually includes a lock that slips into a fluke, which extends outwardly at one end of the belt, and slipping the fluke through a slot formed in the other end of the belt or sealing ring.
Another common type of lock belt seal consists on a bolt passing through flukes, which are bent downwards, and are located at each end of the security belt.
Another type of belt seal consists on a fluke formed by a first end of an angular strap including a plurality of linearly spaced openings, and a cover secured to the other end of the strap, and including a passage through which the fluke extends retractable. The belt has a fastener or screw mounted in the cover in order to mate with the spaced apertures in the fluke. The fluke moves forward and backward at the first end of the strap or another fluke moves forward and backward at the second end of the strap. Both flukes are separated from the second end of the strap and within the openings of the straps. The sealing action is obtained by means of sealing wires or plastic padlocks inserted through the openings of each fluke in order to indicate when the sealing mechanism in the belt seal has been tampered.
The wires used to join the flukes are tied together by means of a lead piece, not with the intention of securing the system, but to indicate that the system has not been opened, and whether the padlock has not been manipulated in anyway. This system has the inconvenience of requiring a key in order to be opened, which the authorized serviceman of the electric power supplier company may not be carrying, may have lost, or the padlock may be damaged by the failed attempts of some user when trying to open it. Thus, when finding such inconveniences, the maintenance task is not performed with an adequate periodicity, and this lack of maintenance may cause failures in the watt-hour meter lecture system, or the electric power supplier company may have to incur in additional expenses when having to constantly change the padlocks.
Another type of sealing ring, belt or strap seal consists on an open ring bearing at one end, and a fluke with a series of horizontal notches on both sides thereof. The fluke is inserted on the other end of the ring inside a ladle, which has side shoulders in order to facilitate the notches obstruction to prevent the fluke from retracting.
Another type of sealing ring, belt or strap seal consists on two substantially identical “U” shaped covers each one placed on each end of the annular strap. In the strap there are some openings or slots located at the lateral walls of each cover. There is an additional slot on each cover, receiving an insert having an opening centrally formed therein. A beaded screw is mounted on the insert of one of the covers, and the opposite end of it passes through the other cover insert at the opposite end of the fastener and is hooked to the insert opening of the other cover. The end of the fastener opposite to the head of the screw has an elongated slot, which is aligned by rotation to the openings in the sidewalls in order to receive a sealing wire or a plastic padlock after the ring has been mounted to attach the watt-hour meter and the meter socket cover. The mechanism has the inconveniences that it may be damaged by failed attempts of some user when trying to open it or the damage in the mechanism may prevent an authorized serviceman from opening the mechanism in order to carry out the periodical maintenance. The impossibility of carrying out the maintenance may cause failures in the lecture system of the watt-hour meter, or incurring on additional expenses when having to constantly change the security mechanisms.
Several examples of the state of the art related to security sealing ring, belts or straps have been published on different U.S. patents, such as U.S. Pat. Nos. 4,008,585; 4,076,291; 4,134,609; 4,149,741; 4,493,230; 4,531,770; 4,934,747; 5,048,881; 5,207,595; 5,704,804; 5,851,038 and 5,944,555. All these security sealing rings, belts and straps present one or more disadvantages, where the following stands out: poor flexibility not being able to be used more than once, complex mechanism, complex installation, high production costs, need of specialized means (keys, padlocks, sophisticated tools, etc.) in order to remove the security sealing rings, belts and straps. It is necessary to point out that the above-mentioned U.S. patents do not affect the novelty nor the inventive step, as for the security lock mechanisms from the present invention are totally different from the ones in the above-mentioned U.S. patents.
It is important to mention that on May 18, 1999, the same inventor of this invention filed Mexican Patent Application No. 994595 entitled “Single use security sealing ring for watt-hour meters”. The single use sealing ring presents an irreversible hooking system; that is to say, once the sealing wire is destroyed, the system cannot be used again, which makes it disposable. In contrast, the sealing ring of the present invention can be opened once the sealing wire is cut by the maintenance serviceman from the electric power supplier company and can continue or extend its use by installing a new sealing wire. Furthermore, the single use sealing ring presents a much higher production cost because the materials making up the single use sealing ring are structurally robust, while the double fluke sealing ring of the present invention requires materials with less thickness for its production. In conclusion, the double fluke sealing ring presents superior characteristics than those offered in the single use sealing ring by being more versatile in its functionality and structurally more simple.
An object of the present invention is to solve problems associated with the use of mechanisms currently offered in the security sealing rings or straps that are constructed with very complex mechanisms withhigh replacement costs to the electric power supplier company, either due to the replacement of the security sealing ring mechanism or due to the replacement of the watt-hour meterthat may break when tampered with.
One object of the present invention is to provide a security sealing ring which offers advantages, such as easy installation due to the simplicity of the mechanism, easy detection of a violated or altered security sealing ring, tamper resistance, multiple use with the purpose of facilitating and diminishing the maintenance service costs, and a reduced price compared to the security sealing rings currently offered in the market.